Yes, indeed. And they'll apply to the rest of Para-British.
The phonology (and orthoepy) is basically English, idealized a bit.
I. e. it is a combination of features that probably don't occur
together in any particular accent. To use English examples:
<r> is pronounced in all positions, including cases like _there aRe_
and _suRprise_.
<wh> differs from <w> and is never equal to <h>.
_hurry_, _berry_, _carry_, _mirror_, _furry_, _caring_ have different
stressed vowels.
_For_ is not homonymous with _fore_.
The unstressed vowel in _houses_ is [I] rather than [@].
However, all main accents of English are considered 'correct' on the
less formal level.
Indeed, I found the English spelling rules insufficiently 'conlangish'.
A few disambiguating conventions, thorn, and some diacritics were added.
(No, it wasn't the recent discussions of spelling reform that inspired
me...) ;)

>I suppose the thorn stands for
>/T/ (do you have edh for /D/? or only thorn for both?),

No. 'Thorn' is [D], and <th> is always [T]. Edh is not used. Kench
evolved from a dialect that had all word-initial spirants voiced in
the 'Middle English' stage.

>and <e> in an
>ending stands for /@/ (by comparison with other Germanic langs),

Word-final <e> is silent (as in English, but more uniformly so).

>but are
>the diphtongs the same as English?

Yes, mostly. But <ow> is always as in _show_, words like _how_, _now_
would be spelled with <ouw>; <ei> is as in British (not American)
_either_ (the vowel in _eye_); <aa> is the stressed vowel in _father_;
<ea> is always as in _steal_, and <ear> always as in _clear_; <ough>
always sounds as in _drought_ (other readings are denoted <augh>, <uff>,
etc., since <gh> is always silent by itself and doesn't alter the
vowels, except for lengthening them); <oo> is always long.
A few remarks about diacritics (some of them occur in the Paternoster).
Grave means 'short despite open stressed syllable', acute - 'long despite
closed or unstressed syllable'. Diaeresis in <ü> denotes the sound in
_put_; with other vowels it overrides consonant context (in combinations
like <wa>, <all>, etc.) and has some other usages.

>and the <h> in <zhe> and <longhen>,
>what
>does it stand for?

<zh> is [Z]; <ngh> was intended to denote non-final [N] (as opposed to
<ng> or <ngu> denoting <Ng>). Now I doubt if the spelling _longher_ was
correct (it seems that it should have been _longuer_, but _longhen_ is
perfectly OK).
Indeed, I haven't covered all topics...